One type of light-emitting elements has the structure in which a light-emitting functional layer including a light-emitting layer, a conductive layer, and so on are interposed between an anode as a first electrode and a cathode as a second electrode.
The light-emitting layer and the cathode are influenced by gas such as moisture and oxygen (hereinafter, referred to also as gas such as moisture, or simply as gas). Specifically, the light-emitting layer has light-emitting properties that are deteriorated due to moisture or the like, and as a result has a short operating life as an element. The cathode varies in electric properties due to oxygen or the like. Large variation in electric properties disables the cathode to supply electrons to the light-emitting layer, and as a result light emission cannot be performed (so-called display defects are caused).
For this reason, a passivation layer is formed on an upper surface of the cathode for example, in order to protect the light-emitting layer and the cathode against gas such as moisture, in other words, in order to prevent gas infiltration.
On the other hand, the light-emitting layer emits light. The light is externally extracted after transmitting through the cathode and the passivation layer (in the case of a display panel of a top emission type). Accordingly, there is a need for the passivation layer to have excellent light transmissive properties in addition to high gas barrier properties. A silicon nitride (SiN) film is for example used for the passivation layer.
Also, in order to further improve the gas barrier properties of the light-emitting element, there has been proposed an art of forming the passivation layer by an atomic layer epitaxy (ALE) method (for example Patent Literatures 1 and 2).